声衰减与非线性对双频聚焦声焦域的影响

The Effects of Medium Attenuation and Non-linearity on Focal Region of Dual-frequency Focused Ultrasound

目的:探讨声衰减与非线性对双频聚焦超声声焦域的影响。方法:利用瑞利积分的线性叠加算法数值模拟计算,并在辐照离体生物组织中进行实验验证。结果:随着声衰减系数的增大与非线性的增强,双频声焦域从"椭球形"变成"蝌蚪形",并且焦域向着换能器方向移动,但声衰减的影响较非线性大。结论:声衰减与非线性对焦域影响较大,在实际应用中应予考虑。本文在利用瑞利积分的线性叠加算法,研究了媒介声衰减与高声强引起的非线性对差频相干模式下的双频聚焦声场焦域的影响。结果表明,随着声衰减系数的增大与非线性的增加。双频声焦域从"椭球形"变为"蝌蚪形",并且焦域向着换能器方向移动,但声衰减的影响较非线性大。并在离体牛肝的损伤实验中得到初步验证。

Objective： To investigate the influences of sound attenuation and acoustic nonlinearity on the dual-frequency focused ultrasound focal region. Methods： We used Rayleigh integral superposition method to numerical simulation, and used dual- frequency focused ultrasound to exposure the liver in vitro. Results： Dual-band acoustic focal region from the ＂ellipsoid＂ to ＂tadpole-shaped＂ with the attenuation coefficient increases and the non-linear enhancement, and focal region moving toward the transducer, but the sound attenuation than nonlinear large. Conclusions： The attenuation and nonlinear focusing fields greater impact, in practical applications should be considered.